DELTA -- Police said they may spend several more days combing a remote area of the Utah desert for signs of a mother missing since 2009.
West Valley City police Sgt. Mike Powell said teams are making good progress in the search for Susan Powell and want to cover more ground.
"There are a number of areas that remain on our map that we still need to cover," said Powell, who is not related to the missing woman. "We're gonna be here for a couple of more days."
Wednesday's efforts will take searchers about 30 miles north and east of where they have been focused over the past week, Powell said.
Police are working near Topaz Mountain, a popular rock-hounding area about 135 miles southwest of West Valley City, where the mother of two was last seen in December 2009.
Searchers have been working on foot, all-terrain vehicles and horseback for more than a week. Cadaver dogs and a state police helicopter have also been employed. So far, police estimate they have covered more than 50 square miles.
Search and rescue crews from six county sheriff's offices are assisting.
Police haven't said specifically what they are looking for but have recovered numerous items that "don't belong in the natural environment," including blankets and clothing, which are being documented and removed for a closer look, Mike Powell said.
Last week, cadaver dogs led investigators to what appeared to be a shallow grave, but after two days of excavation, police said they had found only a collection of charred wood chips. About 100 pieces of wood have been removed from the site for examination by a forensic anthropologist.
Susan Powell's husband, Josh Powell, has been named the only person of interest in the case, although he's never been arrested or charged.
Police are searching near Topaz Mountain in part because it's about 30 miles south of Simpson Spring, a Pony Express Trail campground where Josh Powell told police he took the couple's young children -- then aged 2 and 4 -- on a winter camping trip in the hours before his wife disappeared. The Powell's 4-year-old son has confirmed the trip to police.
Last month, West Valley City investigators also searched the mine-dotted mountains outside of Ely, Nev., clues in the case.
Investigators have said both searches were triggered by information gathered from search warrants served in the case.
Just after Susan Powell's disappearance, warrants were served on Josh Powell's West Valley City home and the family minivan, which he said he took camping.
More recently, police served a warrant on the Puyallup, Wash., home where Josh Powell and the children now live with family. Josh Powell's father, Steven Powell, has said investigators removed computers and journals belonging to Susan Powell from the home.